Moscow-based wire agency Interfax has reported that Ukrainian rebel forces have the black box and have agreed to hand it over to the Russian-run regional air safety authority.

It is important to know who has the black box because that organization will control the release of the data recordings and information from onboard before the plane hit the ground.

Russian authorities have the ability to read out both the cockpit voice recorder and the flight data recorder, former U.S. National Transportation Safety Board accident investigator Tom Haueter told ABC News.

The rebels, described as armed Russian separatists who call themselves the Donetsk People's Republic, have issued a statement via their spokesman saying they will cooperate with authorities.

"Of course, we most likely will give them to the Interstate Aviation Committee (IAC), to Moscow. High-level experts, who will be able to determine exactly the reason of the catastrophe, work there, though it is clear," Andrei Purgin said to Interfax.

Black boxes are used to review information from the flight data recorder and cockpit voice recorders and officials could be able to determine whether the pilot was aware of any problems before the plane was downed.

Malaysia Airlines Flight 17 had 280 passengers and 15 crew members on its Kuala Lumpur-bound flight that took off from Amsterdam Thursday afternoon.